Generally, a brush holding apparatus in an automotive alternator is mounted internally in a tightly-closed case, making it necessary to dismantle the case during brush replacement, thereby making workability extremely poor.
Thus, automotive alternators in which an opening is disposed in a portion of the case facing the brush holding apparatus, enabling the brushes to be changed through the opening, have been proposed in Japanese Utility Model Laid-Open No. SHO 51-87205, Japanese Patent Laid-Open No. SHO 51-66409, etc., for example.
FIGS. 29 and 30 are a longitudinal section and a plan, respectively, showing a vicinity of the brush holding apparatus of the conventional automotive alternator described in Japanese Patent Laid-Open No. SHO 51-66409, for example, and FIG. 31 is a perspective showing a brush assembly used in the brush holding apparatus shown in FIGS. 29 and 30.
In FIGS. 29 to 31, a rotor 81 is fixed to a shaft 82 rotatably supported in a front bracket (not shown) and a rear bracket 84a by means of bearings 83, being disposed inside a case 84 composed of the front bracket and the rear bracket 84a. Slip rings 85 are mounted to a rear-end end portion of the shaft 82.
A stator 86 is constituted by: a cylindrical stator core 87; and a stator winding 88 installed in the stator core 87, first and second end portions of the stator core 87 being held between the front bracket and the rear bracket 84a, the stator 86 being disposed so as to surround the rotor 81.
A brush holding apparatus 89 is constituted by: a brush body portion 90 through which a pair of brush-housing angular apertures 90a are disposed; and a pair of brush assemblies 95 in each of which a brush 91, a pigtail 92, a brush spring 93, and a brush terminal 94 are assembled integrally. This brush holding apparatus 89 is mounted to the rear bracket 84a by securely fastening the brush body portion 90 to an inner wall surface of an end wall of the rear bracket 84a by means of a screw 96, inserting the brushes 91 of each of the brush assemblies 95 into the brush-housing angular apertures 90a, and securely fastening the brush terminals 94 to the brush body portion 90 by means of screws 97. Thus, the brushes 91 are forced into contact with the slip rings 85 by the brush springs 93.
In addition, an opening 98 for brush replacement is disposed through a portion of a side wall of the rear bracket 84a facing the brush body portion 90. A cover 99 is securely fastened to an outer circumferential surface of the side wall of the rear bracket 84a by means of screws 100 so as to cover the opening 98.
A brush replacement operation of the conventional automotive alternator constructed in this manner will now be explained.
First, the cover 99 is removed by removing the screws 100. Then, the screws 97 are removed and the brush assemblies 95 are pulled out through the opening 98. Next, the brushes 91 of new brush assemblies 95 are inserted into the brush-housing angular apertures 90a, and the brush terminals 94 are securely fastened to the brush body portion 90 by means of the screws 97 while pressing the brush springs 93. In addition, the cover 99 is placed over the opening 98 and securely fastened to the rear bracket 84a by means of the screws 100, completing replacement of the brushes 91.
However, in this conventional automotive alternator, because the cover 99 is mounted to the rear bracket 84a by means of fastening by the screws 100, one problem has been that removal and replacement of the screws 100 is required in a narrow engine compartment, lowering brush replacement work efficiency.